Datasheet LA4182 (Sanyo) - 4

LA4182 Description of External Parts
C1(C2) Feedback capacitor The low cutoff frequency depends on this capacitor. If the capacity is increased, the starting time is delayed. C3(C4) Bootstrap capacitor If the capacity is decreased, the output at low frequencies goes lower. C5(C6) Oscillation preventing capacitor Polyester film capacitor, being good in temperature characteristic, frequency characteristic, is used. If an aluminum electrolytic capacitor or ceramic capacitor is used, oscillation may occur at low temperatures. C7(C8) Output capacitor The low cutoff frequency depends on this capacitor. In order for the low frequency characteristic in the bridge amplifier to be equal to that in the stereo amplifier application, the capacity must be doubled. C9 Decoupling capacitor Used for the ripple filter. Since the rejection effect is saturated at a certain capacity, it is meaningless to increase the capacity more than needed. This capacitor, being also used for the time constant of the muting circuit, affects the starting time. C10 Power source capacitor
Application Circuit 1. Voltage gain adjustment
k Stereo The voltage gain depends on built-in resistors R1 (R2), R3 (R4) as follows : R3 (R4) VG = 20log [dB] R1 (R2) If the IC is used at a voltage gain less than this, the following equation with Rf added applies. R3 (R4) VG = 20log [dB] R1 (R2) + Rf where R1 (R2) = 50 Ω, R3 (R4) = 10 kΩ k Bridge The above shows the bridge amplifier configuration, where ch.1 operates as a noninverting amplifier and ch.2 as an inverting amplifier. The output of ch.1 is divided with R5, R6 and led to pin 1 and then input to ch.2. Since the attenuation degree (R5/R6) of ch. 1 output and the amplification degree (R4/R2 + R6) of ch. 2 are fixed at an equal value, the ch.2 output is in opposite phase with the ch. 1 output. Therefore, the total voltage gain gets apparently 6 dB higher than the voltage gain of ch.1 alone and is determined by the following equation. R3 VG = 20log + 6 [dB] R1 If the IC is used at a voltage gain less than this, the following equation with Rf added applies. R3 VG = 20log + 6 [dB] R1 + Rf No.742-4/10